Add TopstepX platform support, drain withdrawal stages, and perfect-path calendar projection

- TopstepXClient (ProjectX Gateway): API-key auth, SignalR user hub,
  Trade/search daily P&L, emulated OCO exits, books-invariant
  withdrawal detection for $0-start accounts
- Platform-aware client pool, credentials (api_key column), and
  credential form; $0-size account types match by prefix alone
- Drain stages: min-day ($5-$15 randomized) MNQ legs for the
  configured days, then wait for the 50% withdrawal; stage pills
  show 'Stage N – Drain'
- Account calendar projects the perfect path: future days book their
  planned targets, simulated 50% withdrawals, payout marker

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>

app/api/firms/route.ts

@@ -18,11 +18,15 @@ export async function GET() {
     try {
         const result: FirmConfig[] = getCachedCatalog().map((firm) => {
             const creds = getCredentials(firm.id);
+            const hasCredentials = firm.platform === 'topstepx'
+                ? !!creds?.apiKey
+                : !!(creds?.username && creds?.password);
             return {
                 id: firm.id,
                 firm: firm.name,
+                platform: firm.platform,
                 username: creds?.username ?? '',
-                hasCredentials: !!creds,
+                hasCredentials,
                 bannedSymbols: firm.bannedSymbols,
                 accounts: firm.accountTypes.map((a) => ({
                     id: a.id,